Electrical connectors



May 12,1970 A. R. NORDEN ELECTRICAL CONNECTORS 5 Sheets-Sheet 1 Filed Jan. 16, 1968 ay 1 970 A. R. NORDEN 3,512,117

ELECTRICAL CONNECTORS Filed Jan. 16, 1968 3 Sheets-Sheet 2 A. R. NQRDEN ELECTRICAL CQNNECTORS May 12, 1970 3 Sheets-Sheet 5 Filed Jan. 16, 1968 United States Patent US. Cl. 339-40 23 Claims ABSTRACT OF THE DISCLOSURE Separable connectors are formed to include mutually cooperable guide parts that direct one of the connectors lengthwise along a line crossing the other connector at an axis and into assembled relation to the other with respective contact surfaces touching each other, after which relative pivoting of the connectors about that axis causes buildup of firm spring contact pressure. The preferred construction has a spring bridge on one connector and a pivoted channel under the bridge and facing its contact area, the bridge and the channel having cooperable cam parts so that the other connector enters the channel lengthwise and then swings the channel about its pivot to cause cammed buildup of the contact pressure. The preferred embodiment also includes mutually conforming in sulating cases accommodating the assembling and swinging motions and closing the opening in one connector-case that admits the other connector initially.

The present invention relates to devices for making separable electrical connections. Prominent advantages are realized in applying the invention to making connections between the ends of two wires, particularly heavy cables for carrying large values of current. However it will be appreciated that the broader aspects of the invention are applicable to other separable electrical conections, such as in making a connection between a movable wire and a terminal on a fixed structure.

An object of the invention resides in providing novel cooperating connector units, where one connector unit may be inserted into the other and then operated to develop a large value of contact pressure, without resort to inordinate insertion effort and without resort to separately operated contact-clamping mechanisms.

A more particular object of the invention resides in providing a novel separable connector having companion connector units wherein part of one connector unit may be inserted into the other and then operated as a unit in a swinging motion about an axis transverse to the insertion path for establishing ample contact pressure. A further object resides in providing novel separable electrical connectors of this type for concurrently making multiple circuit connections, and for separating such connections concurrently by reverse operations.

A further object of the invention is to provide a novel electrical connector wherein a contact member of one connector unit serves as an actuating element for a companion contact-pressuring means in the other connector unit, first to be plugged-in and thus assembled opposite a companion contact member, and then to be swung about an axis through the contact members, for operating the contact-pressuring means. In this way, separately operated contact-clamping mechanisms can be avoided, the connection being made and pressure being established by a first motion of inserting a contact member of one connector unit into the other, followed by a swing motion to establish ample contact pressure. Further, the swinging motion has the intrinsic advantage of providing leverage for achieving firm contact pressure between a pair of large contact members, and between multiple pairs of contact Patented May 12, 1970 members Where a multiple-circuit connector is involved. Despite this advantage for connectors intended for large values of current, the invention is eminently effective when applied to smaller connectors.

Another object of the invention resides in providing insulating cases for a plug-in connector unit and a receiver connector unit, wherein each insulating case complements the other after they are assembled, in accommodating a swinging motion of one connector unit relative to the other. A related object of the invention resides in providing electrical connectors as aforesaid with a deadfront insulating enclosure that is normally closed but which is automatically opened as one connector unit is assembled to the other, the dead-front enclosure also accommodating relative swinging movement between the connector unit. Another related object of the invention resides in providing insulating cases for companion plugin and receiving connector units that involve relative swinging motion after being assembled, wherein the insulating enclosure of the plug-in connector unit shrouds the opening into the insulating enclosure of the receiving connector unit throughout the range of relative swinging movement.

The nature of the invention in its various aspects, together with the foregoing and other novel features and advantages, will be more fully appreciated from the following detailed description of a presently preferred embodiment thereof and of several modifications of certain features. In the detailed description that follows, reference is made to the accompanying drawings which form part of the present disclosure.

In the drawings:

FIG. 1 is a lateral view of a plug-in connector unit forming one part of a separable electrical connector embodying features of the invention in a presently preferred form, portions of FIG. 1 being broken away and shown in cross-section;

FIG. 2 is a cross-section of the plug-in connector unit of FIG. 1 as viewed substantially along the line 22 in FIG. 1, portions of a companion connector unit that is to receive the plug-in unit of FIG. 1 being shown in FIG. 2 in broken lines, the connector units being shown in their final assembled relationship;

FIG. 3 is a fragmentary lateral view of the connector units of FIGS. 1 and 4, shown assembled as in FIG. 2, with portions thereof broken away and shown in crosssection to reveal internal details;

FIG. 4 is a lateral view of the connector unit shown in FIGS. 2 and 3, which is to receive the plug-in connector unit of FIG. 1, portions of FIG. 4 being broken away and shown in cross-section, this connector unit being shown in condition to receive a companion plug-in connector units;

FIG. 5 is a horizontal cross-section of the connector unit of FIG. 4, asviewed substantially at the line 5-5 in FIG. 4;

FIGS. 5A and 5B are transverse cross-sections of the connector unit of FIG. 5 as viewed from the planes 5A5A and 5B5B in FIG. 5;

FIG. 6 is a fragmentary perspective view of a modification of the contact members and pressure-applying means of FIGS. 1-5, embodying further features of the invention;

FIGS. 7 and 8 are fragmentary cross-sections of the structure in FIG. 6 as viewed from the planes 77 and 88, respectively, in FIG. 6;

FIG. 9 is a plan view of a modification of a portion of the structure in FIGS. 4 and 5;

FIG. 10 is a cross-section of the structure in FIG. 9 as viewed from the plane 10-10 in FIG. 9;

FIGS. 11 and 12 are cross-sections of further modifications of the structure in FIG. 10.

Referring now to the drawings and particularly to FIGS. 1-5, 5A and 5B, the preferred embodiment may now be described.

In FIG. 1 a plug-in connector unit is shown comprising two male plug-in contact members 12 and 14 that are fixed in assemb y to each other and to a solder lug 16 by a nut-and-bolt assembly 18. The bare end portion of insulated wire 20 is staked, soldered and otherwise secured in lug 1 6.

Another pair of contact elements 12a and 14a are also shown in FIG. 1, connected to insulated wire 20a, by structure the same as that already described.

The entire connector structure is covered by a case of molded insulation, leaving projecting portions of contact members 12, 14, 12a and 14a exposed. The insulating :ase includes a top member 22, an intermediate member 24, and a bottom member 26 that are suitably united as oy screws. The insulating case may be taken apart readily for securing wires to the solder lugs. Three plate-like ex- :ensions 22a, 24a and 26a of the insulating case extend lbOVC and below the projecting portions of the contact members. The insulating structure includes lateral wall portions 28 (see FIG. 2), and it has a cylindrical inner iurface 30 about contact members 12 and 14. The cylinirical axis is located at a pivot point 32 about which conlector unit 10 swings, as one motion in tightening or .oosening connection between the connector units.

The connector unit 33 that is to receive the plug-in :onnector unit 10 is shown in detail in FIGS. 4, 5, 5A and 5B. Contact member 34 in these figures is fixed to solder ug 36 by a nut-and-bolt assembly 38. An insulated wire 10 is to have its end stripped and inserted into solder lug 56, suitably secured therein.

Assembled to the top and bottom of contact member 54 is a portion of a clamping mechanism designed to re- :eive the plug-in contact members 12 and 14 which then ierve additionally as part of the contact-clamping mechalism. Plug-in contact members 12 and 14 act as levers 'or actuating the portion of the clamping means shown n FIGS. 4 and 5. The clamping mechanism includes luplicate bridge structures 42 above and below contact member 34, secured to that contact member, as by rivets l4 extending through spacing collars '46. The spacing colars establish a definite space between each of the bridge ltI'LlClIIlIfiS 42 and the contact member 34. A channel mem- )er 48 is disposed in each of these spaces above and beow contact member 34, the open side of each channel acing the contact member. A pivot pin 50 (see also "168. 5A and 5B) suitably secured in the bottom wall if each channel extends through a hole in a respective vridge structure 42. Pivot pins 50 coincide with axis 32 n FIG. 2.

The receiving connector unit 33 includes a three-part ase of molded insulation including parts 52, 54 and 56. The assembly of parts described above, including parts 4, 36, '42 and 48, is contained between parts 54 and 56 )f the insulating enclosure. A like assembly of parts is ontained in the space between parts 52 and 54 of the nclosure for making connection to insulated wire 40a. The center part 54 of the case has a recess 54a for receivng extension 24a of plug-in unit 10 (FIG. 3). Openings 8 are provided in the insulating case opposite the spaces .bove and below contact member 34 so that the insulating ase includes a bar 60 opposite the end of contact memer 34. By like token, the insulating case for the upper ontact member assembly includes dual openings, divided y an integral insulating bar 60a. Openings 58 are of imited arcuate extent, from one edge 62 to an opposite dge 64 (FIG. 5). These openings are normally closed by lugs 66 of insulating material that are biased toward ach other by one-turn springs 68 that are thin corrugated /ashers so as to have several points of tangency to rings 6 and to the opposite surfaces of casing 54 and 56.

These springs normally press the rings against the opposite sides of contact member 3 4. Contact members 12 and 14 have chamfered tips 12' and 14' (FIG. 1) that are to cooperate with complemental chamfers 66 when the plugin connector unit 10 is first being inserted into receiving connector unit 33. These chamfered tips 12' and 14' spread rings 66 apart as the lateral contact surfaces of contact members 12 and 14 move into position at the opposite lateral contact faces of contact member 34 (FIG. 3).

Each bridge structure 42 is formed of a double thickness of leaf-spring stock in which bumps 42a are formed at three locations spaced apart about each pivot 50, these bumps projecting toward contact member 34. The bumps are received in correspondingly spaced-apart cavities 48a in the outside surface of each channel 48, remote from contact member 34, when the channels are in the position illustrated in FIG. 5. This is the position of the channels when the contact members 12 and 14 are initially inserted into the connector 33 of FIGS. 4 and 5. Rivets 44 and their spacing collars 46 form stops limiting the rotation of channel 48 clockwise (FIG. 5) for 10- cating channels 48 in their contact-receiving position.

The plug-in connector unit of FIG. 1 is initially inserted into the connector unit of FIG. 5, moving along an insertion path that is prominently angled in relation to the receiving connector unit. The insertion path is along the cross-section line 5A5A in FIG. 5. The depth of insertion of plug-in connector unit 10 is limited by the engagement of shoulders 12 of male contact member 12 with the side walls of channel 48. During insertion, the lateral contact faces of male contact members 12 and 14 slide across the opposite faces, i.e., the lateral contact faces, of contact member 34. After the plug-in motion is complete, with shoulders 12 of contact member 12 engaging the ends of channel '48, p ug-in unit 10 is swung counterclockwise as viewed in FIG. 5 relative to receiving connector unit 33. The swinging motion of channels 48 in this direction is limited by spacing collars 46 of connector unit 33 (FIG. 2). During this swinging motion, the surfaces of cavities 48a act as camming surfaces that drive bumps 42a of the bridge structures away from contact member 34; but because rivets 44 prevent the separation of the bridge structures, the latter provide enormous spring pressure that drives channels 48 and the contact members 12 and 14 therein toward the contact member 34. In this way, the swinging motion develops enormous contact pressure of the lateral contact surfaces of male contact members 12 and 14 against the opposite lateral contact faces of contact member 34. The contact members 12 and 14 swing about an axis 32 (FIG. 2) that extends through the contact faces, perpendicular thereto. The only eflFort involved in building up the contact pressure is forcing the bumps 42a to rise out of the cavities 48a. Bumps 42a are shown in contact with flat portions of channels 48 in FIG. 3, the contact pressure being fully developed at this point.

Contact members 12 and 14 operate as the actuating portion of a contact-clamping means which comprises channels 48 and bridge structures 42. It is seen that one portion of the clamping means forms a unitary part of plug-in connector unit 10 while the remainder of the contact-clamping mechanism forms a part of the receiving connector unit 33. Notably, however, each connector unit involves no external contact-clamping parts that are movable separately. This promotes simplicity of operation and it also makes for virtual immunity of the twopart connector assembly to harmful elfects of dirt which might otherwise interfere with the operation of a separate contact-actuating mechanism.

The description of contact members 12 and 14 and their operation in relation to contact member 34 is, of course, duplicated by contact members 12a and 14a in relation to the companion structure within receiving connector unit 33. All of the male contact members swing about a common axis during the swinging motion used for build-up of the contact pressure. The endwise plugin motion of the male contact members followed by swinging motion about the axis transverse to the lateral contact faces is very well suited to developing a large amount of contact pressure when the areas of the contact faces are large and where there are multiple pairs of contact members in the connectors. The swinging motion of one contact member relative to the other about an axis through the contact faces inherently provides substantial leverage that facilitates manual operation.

The bumps 42a are formed in leaf-spring stock, and cavities 48a are formed in members of tough steel or other metal chosen for resistance to wear. Consequently, no reliance is placed on wear-resistance of contact members 12, 14 and 34. Accordingly, the contact members can be made of bare copper or copper that is plated with tin or silver, or other suitable metal of low contact resistance.

Various modified forms of contact structures and contact-clamping means are shown in FIGS. 6-12, exclusively. In each of these figures, no effort has been made to show the enclosures, but it will be understood that enclosures such at that shown in FIGS. 1-5, 5A and 5B are contemplated.

Referring now to FIGS. 6, 7 and 8, a receiving connector unit 70 is shown in condition to receive a plugin contact member 72. Receiving connector unit 70 includes a contact member 74 as of copper to which there is secured a bridging structure 76 by suitable supporting and spacing elements 78. Bridging structure 76 advantageously is of leaf-spring stock having bumps 76a formed therein symmetrically opposite a pivot hole 76b in a bridge structure. Slot 760 formed in bridge structure 76 is narrow and is proportioned to receive a short raised key 72a on one lateral face of contact member 72. The length of key 72a measured along member 72 is equal to the diameter of pivot hole 76b. The lateral surface of member 72 at opposite sides of key 72a is crowned so that member 72 is progressively thinner toward its lateral edges. The side of member 72 opposite the key 72a is preferably flat and forms a lateral contact face, for engagement with the surface of flat contact member 74 tthat carries bridge structure 76.

For assembling the plug-in and receiving connector units, cont-act member 72 is moved lengthwise so that key 72a enters slot 760 until the key reaches pivot hole 76b. Member 72 is then swung clockwise as viewed in FIG. 6 until it is aligned lengthwise with member 74. The bumps 76a slope as is illustrated in FIG. 8 and cooperate with the sloping face of member 72 at opposite sides of key.

72a during this swinging motion, resulting in a build-up of contact pressure between the lateral contact surfaces of members 72 and 74. Member 72 acts both as a lever and as one part of a contact clamping mechanism which cooperates with bridge structure 76 and its camming bumps 76a forming another part of the clamping means for building up contact pressure. While member 72 may be a unitary piece of copper or other suitable metal chosen for low resistance and low contact-resistance, the surfaces of member 72 that are to cooperate with camming bumps 76a may have a hard metal overlay for resisting wear. Contact member 72 swings about an axis transverse to the engaging lateral contact faces of members 72 and 74; and in the construction of FIGS. 6-8, the resulting connector has many of the attributes of the connector, in FIGS. 1-5. Thus, movable pairs of contact members can be operated for building up large amounts of contact pressure by virtue of the leverage that can be applied about the pivotal axis. Also, the plug-in connector unit and the receiving connector can each be provided with its own insulating case to form a unit that is relatively immune to dirt of the environment, and no separate mechanism need be employed for operating the contact-clamping means.

FIGS. 9-12 shows three other modifications of internal parts of the receiving connector unit in FIGS. 4, 5, 5A and 5B.

In FIGS. 9 and 10, a contact member is shown, together with a bridging structure 82, assembled to the contact member 80 by rivets 84. Channel 86 has a male screw-threaded part 88 that is threaded into a companion female thread in bridge structure 82. Dished spring washers 90 under the heads of rivets 84 apply resilient pressure to bridge structure 82 and to channel 86.

The channel is shown in FIGS. 9 and 10 in position to receive the male contact member such as member 12, of a plug-in connector unit. Swinging motion of an inserted male contact member with its lateral contact face pressed against the upper or lateral contact face of contact member 80 tends to operate the threaded member 88 in that direction to cause build-up of the contact pressure between the lateral contact faces.

The embodiment in FIG. 11 is very similar to that in FIGS. 9 and 10. The parts in FIG. 11 bear the same numerals as those in FIG. 10, distinguished by the letter a. In FIG. 11, however, bridge structure 82a is of resilient stock so as to avoid the need for spring washers 90 in FIGS. 9 and 10. The other parts of the connector unit in FIG. 11, and its operation, are the same as previously described in connection with FIGS. 9' and 10, and their description is not here repeated.

FIG. 12 is a further modification, the parts of FIG. 12 bearing the same numerals ar in FIGS. 9 and 10, the numerals in FIG. 12 being distinguished by the letter b. Bridge structure 82b is rigid as in FIGS. 9 and 10. However, a leaf-spring 90b is secured to the bottom of channel 86b, the ends of leaf-spring 90b bearing against the bottom of the channel and the center of the spring being bowed outward toward contact member 80b. During insertion of a companion contact member of the plug-in connector unit, the male contact enters the space between spring 90b and contact member 8019; and thereafter, swinging motion of the plug-in contact and channel 86b which receives the plug-in contact drives channel 86b toward contact 80b for building up the contactapplying pressure of spring 90b.

Each of the embodiments in FIGS. 9 and 10, FIG. 11 and FIG. 12 include a contact clamping means in which the elements producing the driving force for increasing the contact pressure during the swinging motion of the plug-in contact element are identified with the receiving connector unit, being in this respect like the embodiment of FIGS. 1-5, 5A to 5B. The companion plug-in element may be that shown in FIG. 1, where the contact member serves the dual functions of providing electrical contact and being the operating portion of the contact clamping means.

It will be appreciated, of course, that dual bridges and assorted contact-pressuring means may be employed at opposite sides of the contact member in each of FIGS. 6-12, in the manner shown in the embodiment of FIGS. 1-5, 5A and 5B. Still other modifications and varied application of the foregoing embodiments will readily occur to those skilled in the art. Consequently, the invention should be broadly construed in accordance with its full spirit and scope.

What is claimed is:

1. A separable electrical connector including first and second connector units that include an elongated plug-in contact member and a cooperating contact member, respectively, having mutually engageable lateral contact faces, said connector units having:

(a) mutually cooperating means for constraining the connector units when assembled to swing about an axis extending through said contact members and at least approximately perpendicular to said lateral contact faces so that wiping contact motion occurs during relative swinging motion of the connector units about said axis from an initial plug-in relationship to a final, operating relationship;

(b) contact clamping means for building up contact pressure during said relative swinging motion, one of said connector units including at least a portion of said clamping means cooperating with a unitary portion of the other of said units, the latter unit then acting as an operating lever of the clamping means; and said connector units having (c) mutually engageable means operative when the connector units are being assembled for directing said elongated plug-in contact member to move lengthwise along a path crossing said aXis and into said initial plug-in relationship with the lateral contact faces disposed for mutual wiping contact during the ensuing swinging motion of the connector units,

whereby said connector units may be easily assembled by an initial lengthwise inserting motion of said elongated plug-in contact member and thereafter the operating contact pressure may be established by relative swinging of the connector units into their final, operation relationship.

2. A separable electrical connector in accordance with claim 1 wherein said axis extends through said lateral contact faces in both said initial and final relationships of the connector units.

3. A separable electrical connector in accordance with :laim 1, wherein said lateral contact faces are substantially flat.

4. A separable electrical connector in accordance with :laim 1 wherein said axis extends through said lateral con- :act faces in both said initial and final relationships of :he connector units, and wherein said lateral contact faces are substantially flat.

5. A separable electrical connector in accordance with :laim 1, wherein said first and second connector units in- :lude respective cases of insulation having complemental arcuate formations accommodating said relative swinging notion about said axis.

6. A separable electrical connector in accordance with :laim 1, wherein said first and second connector units in- :lude respective cases of insulation having complemental arcuate formations accommodating said relative swinging notion about said axis, the insulating case of said second :onnector unit having an opening to admit the contact nember of said first connector unit during the initial plugn motion, and the case of said first connector unit having I. portion covering said opening in said final relationship )f said connector units.

7. A separable electrical connector in accordance with :laim 1, wherein said first and second connector units nclude respective cases of insulation having complenental arcuate formations accommodating said relative winging motion about said axis, the insulating case of aid second connector unit having an opening to admit aid elongated contact member and to accommodate winging movement thereof, the insulating case of said irst connector unit having shrouding portions covering :aid opening during said relative swinging motion beween said initial and final relationship of said units.

8. A separable electrical connector in accordance with :laim 1, wherein said second connector unit includes an nsulating case having an opening to admit and accomnodate arcuate movement of said elongated plug-in conact member, and wherein said second connector unit has .n insulating case including wall portions shrouding said rpening throughout said relative swinging motion between aid initial and final relationship.

9. A separable electrical connector in accordance with laim 1, wherein said second connector unit includes 11 nsulting case having an opening to admit and accomnodate arcuate movement of said elongated plug-in conact member, and wherein the case of said second conlCCtOI' unit includes an internal spring-biased member lormally closing said opening and movable by said elongated plug-in contact member to accommodate plug-in and arcuate motions of the plug-in contact member.

10. A separable electrical connector in accordance with claim 1, wherein said elongated plug-in contact member has a formation cooperable with a portion of said second connector unit for establishing said axis as aforesaid.

11. A separable electrical connector in accordance with claim 1, wherein said second connector unit includes a pivoted member complemental to said elongated plug-in contact member for limiting the plug-in motion of the latter and establishing said axis as aforesaid.

12. A separable electrical connector in accordance with claim 1, wherein said connector units include cooperable pivot and bearing formations for establishing said axis.

13. A separable electrical connector in accordance with claim 1, wherein the portion of said clamping means in said second connector unit includes a restrained structure separated from said cooperating contact member to provide a space for admitting said elongated plug-in contact member, said restrained structure and said plug-in contact member having camming portions cooperating with each other during said relative swinging motion for forcing said plug-in contact member laterally against said cooperating contact member.

14. A separable electrical connector in accordance with claim 1, wherein the portion of said clamping means in said second connector unit includes a restrained structure separated from said cooperating contact member to provide a space for admitting said elongated plug-in contact member, said restrained structure and said plug-in contact member having camming portions cooperating during said relative swinging motion for forcing said plug-in contact member laterally against said cooperating contact member, said restrained structure and said plug-in contact member also having cooperating pivot and bearing formations, respectively, for establishing said axis.

15. A separable electrical connector in accordance with claim 1, wherein said connector units include plural plugin contact members and plural cooperating contact members coacting in pairs to provide plural separate current paths, all said plug-in contact members being concurrently insertable and then swingable about said axis relative to said cooperating contact members.

1 6. A separable electrical connector in accordance with claim 1, wherein the contact clamping means of said second connector unit includes resiliently restrained camming means and a camming member pivoted at said axis and cooperable with said resiliently restrained camming means, said camming member being cooperable with and operable by said plug-in contact member when the latter is inserted into said second connector unit lengthwise and moved through said swinging motion as aforesaid, to force said plug-in contact member laterally against said cooperating contact member.

17. A separable electrical connector in accordance with claim 1, wherein said contact clamping means of said second connector unit includes a bridge structure separated by a space from said cooperating contact member, a channel in said space pivoted at said axis to said bridge structure, said channel having an open side facing said cooperating contact member and proportioned to receive said elongated plug-in contact member slidably, the back of the channel having means cooperating with said bridge structure for forcing said lateral contact face of said plugin contact member against the lateral contact face of said cooperating contact member during said swinging motion.

18. A separable electrical connector in accordance with claim 17, wherein said bridge structure is of leaf-spring material to provide resilient contact pressure.

19. A separable electrical connector in accordance with claim 17, wherein said bridge structure and the rear of said channel have cooperating cam surfaces forming said means for forcing said lateral contact faces together.

20. A separable electrical connector in accordance with claim 17, wherein said plug-in contact member and said channel have cooperating formations limiting the plug-in motion and thereby establishing the relative orientation of the plug-in connector units during said relative swinging motion.

21. A separable electrical connector in accordance with claim 17, wherein said bridge structure is of leaf-spring material to provide resilient contact pressure, and wherein said bridge structure and the rear of said channel have cooperating cam surfaces for forcing said lateral contact faces together as aforesaid.

22. A separable electrical connector in accordance with claim 17, wherein said bridge structure is of leaf-spring material to provide resilient contact pressure, and wherein said bridge structure and the rear of said channel have cooperating cam surfaces for forcing said lateral contact faces together as aforesaid, said plug-in contact member and said channel having cooperating formations limiting the plug-in motion and thereby establishing the relative orientation of the plug-in connector units during said relative swinging motion.

23. A separable electrical connector in accordance with claim 17, further including a second elongated plug-in contact member insertable at the side of said cooperating contact member remote from the first-mentioned elongated plug-in contact member and fixed to the latter for operation therewith, and further including another bridge structure, pivoted channel and contact-clamping means as aforesaid for forcing said second plug-in contact member against said remote side of said cooperating contact member during said swinging motion.

References Cited MARVIN A. CHAMPION, Primary Examiner I. H. MCGLYNN, Assistant Examiner US. Cl. X.R. 

